body {
  font-family: sans-serif;
}

#controlPanel {
  float: left;
  padding-top: 30px;
}

.button {
  background-color: gray;
  color: white;
  border-radius: 10px;
  padding: 20px;
  text-align: center;
  margin: 90px 40px;
  cursor: pointer;
}

#traffic-light {
  height: 550px;
  width: 200px;
  float: left;
  background-color: #333;
  border-radius: 40px;
  margin: 30px 0;
  padding: 20px;
}

.bulb {
  height: 150px;
  width: 150px;
  background-color: #111;
  border-radius: 50%;
  margin: 25px auto;
/*  transition: background 500ms;*/
}